I suggest that you add the penalty timer to your profile in the Resistance Hero section to let you know how long it will be before you can support another resistance war.
Currently the only way to know is to move to the region and attempt to support the Resistance war. At that moment you are told how long it will be before you can support or your support goes through.
I suggest you simply move this timer notification to your profile. Click on the Resistance Medal area and see your current timer status.
This will save on traveling costs and make planning Resistance Wars much easier.